Only a One Time Thing
by Cayster
Summary: What if Sebastian didn’t run off and broken up with Annette that one day, but stayed in and received his prize from Kathryn? Feelings begin to take footholds in his life he never thought he'd have for the one woman he was never able to have. [Complete]
1. Receiving His Winnings

"Just a One Time Thing" by Cayster

Summary: What if Sebastian didn't run off and broken up with Annette that one day, but stayed in and received his prize from Kathryn?

DISCLAIMER: I do not own "Cruel Intentions" or any of its characters. Also, I do not own Roger Kumble's "Cruel Intentions" and I do not benefit from it.

Author's Notes: I took the dialogue from the original script of Roger Kumble so if there are differences in the movie with the script please don't think I just pulled it out of my head. But when Kathryn asks, "Is that what you think?" everything from that point on is by me. Though, the descriptions prior from that point are mine.

Also, I'm not an ordinary writer who likes the use of vulgar words to elaborate their story better, but since the characters are regular "cursers" so to speak, I have to grudgingly make them as authentic as possible and use them. Yikes. So I, in advance, apologize for the any use of words you do not agree with.

Chapter One: Receiving His Winnings

The sun's bright, radiant rays crept through his blinds causing a pattern of lines across his floor. He rarely gave any thought on the sun's warmth or the beauty it contrasted against the clouds. After all, Sebastian didn't have time to think about petty little absurdities these days; he wasn't a pansy like that.

He was a little on the edge as he stood there talking on the phone with Annette. She was the only girl who had ever given him a chase— well, except for Kathryn.

As Annette said her good-bye and sent her love, Sebastian chimed softly, "I'll pick you up in an hour. I love you too."

Sebastian wasn't great with the entire mushy love thing, if that's what society called it these days. It was a little too over-the-top and cliché for him to like it very much. Hypocrites used it intolerably too often. Bastards!

As he hung up the phone and took a seat on his desk, thoughts kept channeling through his mind, the majority being on Annette and if he really felt that way about her or not. But every thought dissolved once he saw his leering step-sister, Kathryn, in his doorway.

She had a smirk on her face which he detested with his whole being, but it also intrigued him as to what she was simpering about.

"Oh my God. You're completely p-whipped," Kathryn exclaimed as she entered his bedroom slowly.

Sebastian crossed his arms defensively but his toned stayed calm, "No, I'm not."

"P-whipped, p-whipped." She mocked with a sneer about her. Sebastian could tell the she was none too happy.

"What's wrong with you? Why are you acting this way?" He asked as he stood up slowly getting up off his desk.

Tears started to evaded her russet brown eyes and a pained expression covered her face where the mockery once was. Slowly, Sebastian soon started to soften his cynical air.

Kathryn wiped her tears hastily away; Sebastian knew she hated being vulnerable. "I'm sorry. It's just upsetting. You're in love with her." She kept coming closer to him as she spoke until she was just inches away, "You don't love me anymore."

Sebastian was a little uneasy by the thought of Kathryn crying let alone being self-conscious that he wasn't in love with her, but with Annette. Right now he didn't even know himself which one he loved more— he was just as confused as Kathryn was.

"Oh come on, Kathryn, it was just a contest." His voice was a little too harsh than he intended.

She looked exasperated and fretful, "At first it was, but now it's become something bigger." Tears still silently made their way down her soft, now wet cheeks.

He felt guilty, rather guilty. He prided himself on not being guilty once he committed an act and was a firm believer in Macbeth's 'what's done is done' philosophy. But now, Sebastian regretted the whole bet in the first place because it fucked up his life royally. She was so innocent at this moment, the first time he had ever seen her like that. It scared him and shocked him.

"Kathryn, you know I love you. I've always loved you." His voice was a little shaky, but it wasn't forceful or belligerent like it usually was in its casualness. This time it was more soft and pure.

"Not anymore you don't," she shook her head, not believing a word he was saying and it pissed Sebastian off. "It's obvious."

Obvious? Obvious! No. Did she really believe that Annette was his 'love of his life' or some term people use obsessively once they like someone? His heart started to race out of annoyance and frustration.

Sebastian's anger was evident when he proclaimed, "I can't believe you're reacting this way. You're just saying this because you lost the bet."

He swiftly walked past her to the opposite side of his room where his door was. Sebastian was determined to just get the hell out of Kathryn's presence for a while.

But once she called, "Is that what you think?" It stopped him in his tracks, making him look back at her out of curiosity.

Sebastian only nodded in response; he didn't want to speak to her right at the moment.

After a few seconds of staring at him, which didn't cause Sebastian to sweat like it usually did, Kathryn leisurely walked over to his bed and sat down on it. Tears were still falling, but that didn't deter her straightforwardness. Sebastian knew exactly what she was implying as she was sitting there staring at him with an intensity he never saw radiate from her before. It was dangerous for him to be drawn into, but at the same time, it would be idiotic as not be captivated by it.

"Let's get this over with," Kathryn softly said just above a whisper as if she was both nervous and excited.

Sebastian stood grounded for a second, stunned. But soon his daft shock was closed off as well as reasoning. He took a step over towards Kathryn cautiously as if expecting her to flippantly change her mind like she did with many other guys. But once he saw that she was serious and undeterred with his guard he was putting on, Sebastian steadily over to her.

As he stood in front of her, Kathryn mildly looked up at him. Her tearstained cheeks, which only proved her vulnerability more, made her even more endearing to him in way that she never touched upon before. It was like she was like Annette, innocent and genuine. He couldn't remember a time when that prevailed beyond her wild, devilish front.

"This is the only time, you know?" She reminded him, her voice was tranquil and controlled, but her eyes were depicting a much different story. They were soft, emotional not cold and bear.

"It won't happen again," Kathryn continued at the same rate, trying to make her point clear.

Sebastian nodded unhurriedly, "I understand." He raised his hand from his side and cautiously cupped Kathryn's face, which in turn she closed her eyes. "I'm not asking for more than this," he added causing her eyes open quickly.

She was obviously a little surprised by his control or at least his ability to only ask for what he deserves. He had always been precocious in getting what he always wanted and more, but this was different; he was content with what he was receiving.

"I-" Kathryn began again, but Sebastian interrupted her when he leaned down and kissed her gently.

The kiss wasn't rushed or fervent, but softly and slow. It was like they were relishing in the kiss because it was a barrier in which they had never broken through and they wanted to reward themselves for it. Soon though, the kiss escalated into a passionate, fiery kiss which Sebastian couldn't compare it to any other which he delved in.

He was amazed that he was filled with elation unlike anything he had ever known. Sebastian was never affected this way by anyone— not even when he was with Annette, who he had grown to care for. But the feeling was not to the point of overwhelming him just causing him to be even more passionate.

Kathryn started to unbutton his black button-down, but she kept fumbling with the buttons. "Fuck it!" She exclaimed when she pulled fiercely on the shirt causing the buttons to rip off, raining to the ground.

"Hey that's my favorite shirt!" Sebastian said accusingly, breaking away from their kiss, standing to his full height.

She pushed the shirt off of his shoulders and it lightly hit the ground, forgotten. A mischievous smile was dancing on her full lips as she looked up at him. And then out of no where, she grabbed his white t-shirt and pulled him down on top of her, "You'll get over it."

Sebastian laughed at the remark because he knew he would get over it as soon as he went and bought a new shirt.

Immediately they began to kiss again; taking in each other's sweet intoxications. Neither one of them was letting on how much they were enjoying this little adventure, but both of their hearts were racing and just wanted more of the other. They were not doing this because of the bet any longer, even though that was their excuse; they were doing this because they wanted it— both of them did.

For the next couple of hours Sebastian received his winnings and much more. This day surpassed many times before and probably many times ahead. He knew his heart that it wasn't just sex, it was love intertwined with them, but he wasn't going to admit that. Sebastian wasn't naïve to think Kathryn would say it was. She was going to forget the whole thing happened in an hour or so, but he was expecting that or else how would they function like the horrible duo that they were?

Author's Notes:

All right, now I just want to tell all of those people out there wondering why I didn't just write the whole sex bit. Well, to tell you the truth, I'm not a smut writer; I'm an angst writer mainly. Plus, I'd probably be horrible at writing it. So that's why I didn't want to ruin my story and taint my writing style. It's better left unsaid in my stories than actually said sometimes— it's up to you guys to see how it happened.

This is just the first chapter of a two chapter story. So if you were thinking that that was a crappy ending, no need to fret there's a second chapter. And hopefully you already noticed that this is a Kathryn/Sebastian fic not a Sebastian/Annette fic.

Thanks so much for just taking the time to read this! It means a whole heck of a lot to me. I'm so ecstatic each time I know that someone's just reading one of my stories; a humbling experience, really. So, thanks for everything and much, much more. You all rock!


	2. It's Too Late

**Chapter Two**: It's Too Late

**Chapter Note**: This chapter's title is a lyric from Snow Patrol's "Grazed Knees."

The soft, dull patter of rain drops hitting the window was the only noise that filled the darkly painted dorm room. Sometimes a restless huff of exasperation would break the rhythmic display of nature or even a rustle of a page being turned. Other than that though, silence prevailed inside the four walls.

Sunday was usually an ordinary day on campus; laughing and screams were normally heard in the hall or even outside on the luscious, green lawn. But this Sunday was different. The stormy afternoon was causing a content quietness to blanket over the rowdiness and immaturity. Either students were taking this time to leisurely read and study, or even catch up on some much needed sleep.

As for Sebastian though, he was looking at his trophy— his prized journal. He had been staring blankly at one page, her page. Kathryn's picture didn't suit her any longer. Yes, she was still intimidating and manipulative, but he finally knew what was deeper that her rough exterior. Her sharp, intense gaze didn't highlight her eyes like he remembered them that day and he wished he saw their softness more often.

He lightly touched the picture lovingly and felt its coolness.

"Broken," Sebastian softly murmured as he looked at the picture. "You're so defeated and you're beautiful that way."

Since that fateful afternoon, Kathryn and Sebastian barely even felt the tension that densely separated them now. Yes, there were a few awkward moments they encountered since then, but they overpowered those with either changing the subject or suavely finding excuses to leave the other's company. Neither of them spoke of that day; it was like it never happened. Sometimes Sebastian wished that he could have just deflected the tempting offer with his usual arrogant air, but he had wanted Kathryn for so long it was too good of an offer to turn down.

Then again, Sebastian treasured the moment as if it were honey on his lips. He never experienced a situation as awe-inspiring or incredible as that. Sebastian supposed it was the sin that was wrapped up in it as well as Kathryn's unexpected vulnerability too, but deep down in his stomach was the idea of love. Why had that one time been so moving and meaningful was beyond him at the moment, or at least Sebastian didn't want to touch upon the actual reason— it made him uneasy and broody.

Suddenly the loud ring of his black cell phone caused Sebastian to practically jump out of his skin. With his heart racing out of fright, he quickly shut his journal and threw it towards the foot of his bed. He then reached over onto his mahogany nightstand and picked up his phone, which was still ringing endlessly.

Sebastian cleared his throat and then said in a bland tone, "Hello?"

Laughter erupted from the other end of the connection. Immediately he recognized its mockery.

"Why didn't little Sebastian tell me that Annette dumped his ass?" Kathryn asked while still laughing.

Sebastian knew that she was thoroughly relishing this moment because Kathryn hated Annette even more since he collected his reward. Her indifference was starting to piss him off.

A sly smile played mischievously across his lips. "As I recall," Sebastian replied as he looked at his hands, "your ex practically called you a bulimic headcase."

"Aw, now we're going to play dirty now, are we?" Kathryn asked as if Sebastian was an immature child. He especially hated it when she talked down to him.

"You hypocrite!" Sebastian responded with malicious seeping from it. "You're the one who meticulously plans out paybacks in the lowest ways."

"Touché," Kathryn exclaimed and kept laughing softly.

Then there was a knock at his door.

Sebastian looked over at the door grimacing. "Hold on one second, someone's here," he told Kathryn as he got up off his bed and started to walk over to open it and as he did so, on the other side of his thick wooden door was his step-sister, Kathryn.

"Don't look so surprised," she said as she turned off her cell phone and walked into his room. "I thought that I'd chat with you on my way over so I can torture you longer."

Sebastian just gaped at her, hardly believing that Kathryn had the audacity to waltz in his room. He reluctantly closed the heavy door and stood in front of it as he continued to watch her walk over to his sofa and sit down.

"So?" She asked as she looked over at him with a mischievous smile on. "How did it happen? Give me all the painful details, especially when you started to beg for her to stay with you."

"Ha." Sebastian laughed sarcastically feeling extremely agitated. He walked over to his window that was near the sofa's edge. "Actually, we mutually agreed that nothing had to been occurring between us since this summer so we both decided it would be for the best that we wouldn't see each other any longer."

He kept on watching the abstract blur of the falling raindrops hit his window feeling a little dazed from its obscure lines. "She was the one who brought it up so I wouldn't say that I was 'dumped' just merely receiving her vote first."

Sebastian looked over at the brunette, who had been carefully observing his relaxed body language. Her eyes were mirroring interest ferociously and smiled at that fact.

"That's it?" Kathryn asked outraged; she was obviously expecting a dramatic end to a passionate summer heartthrob. There was no traceable smile to be found, only a quiver of disgust.

At this Sebastian looked back out his window and continued to watch the mirage. "Yes, that's the whole dry story."

Kathryn then let out an audible murmur that didn't quite touch Sebastian's ears, but he knew that she wasn't too happy at the juiciest rumor turning out to be unsteady. A small smirk crossed Sebastian's lips and he loved the fact that she was disappointed.

Silence soon overcame the bittersweet rivalry and it stretched for an extended amount of time. They were used to this element of their somewhat dysfunctional relationship which was a repercussion of their infidelity. Neither one looked at the other but both were silently wishing the other to break the raucous silence.

Finally, Kathryn stood up slowly and walked over to Sebastian's bed. The movement caught Sebastian's attention and his eyes followed her over there. She stood there in front of his bed looking down at this journal. Kathryn had been after its very secretive contents ever since she found out about, which was when she and her mother moved into the Valmont mansion. Her face was contorted with curiosity and her eyes scrutinized the cover as if they were burning holes through it.

Sebastian quietly walked over to her and stood slightly behind her. "You still don't know what's in there, do you?" He questioned calmly, not concerned if she were to actually through it now like he had been in the past.

She didn't answer or even move, it was as if she were entranced by the journal sitting in front of her with no protection.

Sebastian took another step so that he was now at angle so look at her properly. Her eyes were dangerously impassioned; a twinkle was present that was rarely in attendance at any other time there. Something overwhelmed Sebastian to let her look at it and even though he was hesitant at the thought he complied anyway.

"Go ahead, look at it." He whispered with a very composed air that surprised him greatly.

At hearing this, Kathryn snapped out of her hypnotic state and looked bemusedly over at Sebastian, who was only a few feet away.

"W-what?" She stammered, flinching at her own clumsiness. Her eyes were depicting confusion and intrigue; apparently, this issue was causing a conflict for her.

He nudged his head towards his beloved trophy that at this point didn't feel so much like a prize anymore. "It's yours to look at," Sebastian said as he walked over to the window again and began to look out at the campus again.

Sebastian felt her eyes burn wholes into him and it was very awkward to endure, but he persevered. The reflection of the glass gave him a clear view of Kathryn just standing over his journal still. He didn't understand why she just didn't pick it up and look at it, was it that difficult to do? He had done it many times with her openly exposed diary so he didn't quite comprehend her behavior; it was unlike her usual manipulative and bluntly impudent self.

A few seconds later though, Kathryn slowly took hold of his journal and cautiously opened it. Sebastian continued watching her from the reflection in the window. She must've opened directly to her chapter and was reading his entries about her deceptive, apathetic, and hateful character.

Kathryn looked over at Sebastian and spat heatedly, "You bastard!"

Sebastian quickly turned around and looked over at her, taken aback. He hadn't expected her to be angry or hurt, but pissed off and venomous were what he was expecting though they were just complements to the first two.

She walked menacingly towards him and stopped directly in front of him leaving barely any room for personal comfort. Kathryn's eyes were starting to be evaded by tears and she did her best to keep them, but the attempt was in vain. She shoved the journal at him.

"Are you trying to tell me how much of a bitch I am without actually saying it or something?" Kathryn asked belligerently.

"No-no, I, ugh, I," Sebastian didn't know what to say. So many ideas were flooding his mind but none of them were sufficient enough or even half believable. "Keep reading!" He exclaimed forcefully when the idea seemed better than the rest.

Perplexed slightly, Kathryn's eyes softened, but her facial features remained sharp with anger.

"You stopped reading too soon; you need to finish reading." Sebastian explained gently yet with conviction entangled within it.

Kathryn huffed and gave him the dirtiest look she must've mustered up.

"Please," Sebastian begged, and begging wasn't something he ordinarily did.

She looked down at the ground and then back up again, but avoiding his gaze. "If you want me to read on so badly, then here," she thrust the journal at him, "you read it."

Sebastian didn't know what to do, but he complied to her wrathful wish. When he was going to begin though, she abruptly turned at started heading towards his door.

"No, Kathryn. If I read, you have to stay here and listen." Sebastian said as he dodged in front of the door just in time. He looked at down at her pleading with his eyes for her to stay. The only thing he received in turn was a cold look of malice and distrust.

"You piece of shit," she mumbled under her breath as she turned around and marched over to the sofa again and slumped down on it.

Extremely nervous now and feeling very overwhelmed, Sebastian cleared his throat as an attempt for those feelings to dissipate, which none of them did.

"Now, when we stand next to each other, the same old feelings make their usual appearance: arrogance, unresolved problems, and revenge. Even those are clearly instated as we're in the same room, there's much more involved now. She's not the same heartless coke addict and I'm not the same audacious son of bitch either, at least not in the same sense we once were towards each other." He took a deep breath to try to keep from his heart exploding in his heart and glanced over at Kathryn quickly. She was sitting there attentively watching him, captivated.

He tried to calm himself some more and continued to read. "We walk on egg shells around each other, whether we'd like to admit that or not, but we do. She hasn't been a tease with other guys since we've been together and I haven't chased any more unsuspecting girls around campus to put in here as a trophy. I suppose it's a mutual agreement we made ever since we woke up the next morning and silently went our separate ways."

Sebastian started to pace slowly throughout his room and straight lines to keep his mind from the nerves. "There's tension separating us, but at the same time it's pushing us together, like a crushing black hole. It's so frustrating and beautiful at the same time how I feel when we're talking or even just sitting in the same room together mutely." Again, Sebastian looked over at Kathryn. This time she wasn't just being enthralled by the excerpt, but her stiffness had disappeared completely and her indifference was no where to be seen. "I suppose you can say we have unresolved sexual tension, but at the same time it's much deeper than any physical aspect. She's always been the one I was never able to obtain and since I have, I can't get past her. She haunts my every thought and I don't know why I can't just forget what ever happened between us that afternoon, but even though I want it all to be gone— I still need it."

He stopped pacing and sat on the edge of his bed not facing her because he knew what the next sentence held and he had never truly uttered the words before with real passion entangling it. "Because if I actually did forget it, then I would be forgetting love… true love." The shakiness of his voice caused his whole body to feel chills.

Sebastian softly closed his journal and placed it on his nightstand. He roughly ran his hands over his face to keep him from getting emotional because he had been when he finished reading. His body was slumped as if he was a failure, which in his mind he kind of was because he had let a girl sweep him off of his feet when it should've been the other way around after all he was the womanizer.

Softly, light footsteps were heard walking towards him. Sebastian looked over his shoulder to see Kathryn walking around the bed and towards him. She sat gracefully down next to him, but remained silent. Sebastian was in awe that she was actually still in the room and not laughing. He was expecting her to start mocking him in attempts to cover up her own feelings. But Sebastian judged her wrongly before hand, making her out to be a villain who had nothing of a soul.

"Sebastian," she whispered wanting him to look over at her.

He slowly turned his head to look at her and when he did she greeted him with a tender kiss. Surprised and caught off guard by the spontaneous gesture they hadn't had since that fateful day. Kathryn pulled back from the lingering kiss and stared fixedly into his eyes. She was starting to come in for another kiss again, but this time Sebastian stopped her he began speaking.

"Kathryn," he began but she interrupted him.

"Just shut-up, Sebastian." She ordered with a mischievous look in her eye.

Obeying her wish, Sebastian remained quiet and she again kissed him and he openly accepted it this time, happily. This kiss was more fervent than the last causing them both to want more of the other to the extremes. Soon they were taking each other's clothes off hastily when a new question overcame Sebastian.

"Kathryn?" He asked in between a kiss, smiling.

"Uh-huh," she mumbled in reply too busy messing with his button-down.

Sebastian smiled and kept kissing Kathryn. "I thought you said this was going to happen only once?" He asked rolling on top of her as he started to unbutton her blouse.

She pushed him back off of her slightly and looked up with him with a certain glint of mischief in her eye. "Sebastian, please. Rules are meant to be broken!"

And at that she roughly pulled him down and on top of her again and kissed him. She was right, Sebastian thought—rules are meant to be broken and this one wasn't any different.

**Author's Notes**:

Well, I just want to thank everyone who read this story and for everyone who showed their support for it as well. You all are so awesome and it's such a humbling experience to be a part of. To be quite honest with you all, I wasn't too happy with ending of the story so if you feel like the ending was too cliché or too vague, I totally agree with you! Again, I just want to thank you all because you guys welcomed me with open arms and I'm very much grateful for that.

I hope to write another Sebastian/Kathryn fic a little later, but it will be a songfic because I found the perfect song to fit their chaotic relationship. Until then!


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